The present invention relates to a method for detecting colour changes in a card design of the pattern of a fabric which might lead to mixed contours in the fabric, by means of a computer comprising central processing means, bus means, detecting means, data entering means, memory means and displaying means, the data of the card design of the pattern of the fabric being entered through data entering means and a processing programme applying correction lift plans to colour changes in a manner known already.
With face-to-face pile weaving in several colours, each warp system in the fabric will comprise all the colours of the pile warp yarns contained in the fabric. When a pile warp yarn is forming a pile, it will move between the upper and the lower fabric and will be interlaced alternately around a weft in each of the said fabrics. When the pile warp yarn is not forming a pile (dead pile), then it will be interlaced in the backing fabric of one of the two fabrics, the pile warp yarns being distributed among the upper and the lower fabric to be interlaced as a dead pile.
In order to obtain an optimal supply of pile warp yarns in the fabric, an exact formation of the shed and a clear view for the workmen replacing and supplying the bobbins of pile warp yarns in the weaving creel, in the weaving creel containing the bobbins of pile warp yarns and from where the pile warp yarns are supplied to the weaving machine, the pile warp yarns being interlaced in the upper fabric are provided at the top of the weaving creel and the pile warp yarns to be interlaced in the lower fabric are provided at the bottom of the weaving creel.
It is known that in pile fabrics, in certain cases, mixed contours or double acting pile warp yarns might occur at a colour change (this being a change of a pile warp yarn forming a pile where a pile warp yarn is no longer forming a pile and is interlaced as a dead pile in the fabric to which it belongs, whereas another pile warp yarn, from its interlaced situation as a dead pile is starting to form a pile in the fabric to which it belongs).
The occurrence of mixed contours means that two tufts of a different pile frame or of a different colour are crossing one another in the face-to-face fabric between two successive wefts in a fabric. Because no weft is separating the two tufts, the two tufts of a different colour have a strong tendency to take up a wrong position with respect to one another (which means that they will not rest against the adjacent tufts of the same colour, but will be situated between the tufts of a different colour) and this will produce a blurred pattern of the fabric.
A double acting pile warp yarn occurring, means that, between two successive wefts in a fabric, there will be found two tufts of a different pile frame or of a different colour running next to one another without crossing one another. In principle, such tufts situated next to one another are taking up a right position however with respect to the formation of the colour, but this position is not very well secured, due to which both tufts may easily change positions which, in turn, will cause the pattern of the fabric to become blurred.
These double acting pile warp yarns will likewise cause the fabric to become locally more closely woven, as locally, the number of tufts will be double the normal number.
Mixed contours occur depending on:                the weave structure (single, double, triple gripper weave structures in combination with the type of weave);        from which fabric the pile warp yarn interlaced starting to form a pile is originating;        in which fabric the pile warp yarn, no longer forming a pile, will be interlaced;        in other words on the position of the pile warp yarns in the weaving creel, since the position of the pile warp yarns in the weaving creel is related to the fabric in which the pile warp yarn will be interlaced as a dead pile.        
In the table below, some examples are shown of situations in which mixed contours (MC) or double acting pile warp yarns (DW) are occurring. The designation (0) means that neither mixed contours nor double acting pile warp yarns are occurring. When designating the colour changes (BT-BT; BT-OT; OT-OT and OT-OT), the first designation is designating the fabric in which the pile warp yarn stops to form a pile is interlaced as a dead pile and the second designation is designating the fabric from which the pile warp yarn starting to form the pile is originating. (BT stands for upper fabric (upper carpet), OT stands for lower fabric (lower carpet).
Weave structureBT—BTBT-OTOT—OTOT-BTsingle gripper 1/1 V0000double gripper ½ VMC0MCMCdouble gripper 1/1 V0DW00three gripper ⅔ V0DW00three gripper 2/2 V0DW00three gripper 1 + ⅔ V0DW00
In the following part of this patent application mention will only be made of mixed contours where, each time, both mixed contours and double acting pile warp yarns are meant.
Such mixed contour effects may be avoided by respecting a number of designing rules. Thus, a designing rule for ½V weaves is stating that in the card design, at a colour change in which two colours are involved, at least one of the two colours should be present along two lines of the same colour (the same pile frame) in the warp direction. In this manner it will be possible to use the method described in the European patent publication EP 927782 and in which of at least one of the pile warp yarns involved in the colour change, one double lift plan before the pile change or one double lift plan after the pile change is replaced by correction lift plans. For in this correction lift plan one colour point is omitted. When this occurs so that the colour point that is omitted is from the colour of which two lines, and therefore two points, are situated one after the other in the warp direction, still one colour point will remain after having applied the correction lift plan.
In practice, such correction lift plans may be applied automatically in the processing software converting the card design (pattern) into a file serving as an input to activate the Jacquard machine.
However, in order to apply this method, as designated, a number of designing rules have to be observed when producing the card design (the pattern). The correction lift plan is only applicable to produce the effect expected when, during two successive lift plans (successive in the warp direction) the pile is formed by the same pile warp yarn. In practice we find that these designing rules are not always applied, so that even when the correction lift plans are automatically applied by the processing software converting the card design into a file serving as an input to activate the Jacquard machine, mixed contours are still occurring.
The designer of the card design does not sufficiently realize when mixed contours are occurring and what is causing them, because possibly he is not sufficiently aware of the rules for designing and the effects caused by not applying them, but mostly because it is not clear to him why these effects are occurring in one situation and not in another situation (more especially, because the final position of pile warp yarns in the weaving creel as well as the weave structure are not known to him).
The persons in the manufacturing department who are carrying out the processing, selecting the texture of the fabric and selecting the Jacquard machine with the accessory weaving creel are unable to take action to adapt the card design where necessary or dare to interfere only slightly, so that mixed contours will continue to occur.
In many cases, mixed contours are only eliminated, when the quality of the pattern of the fabric produced will be affected too strongly. In practice, in many cases the assistance of the supplier of the Jacquard machine or of the processing software will be requested in order to remedy the effects.
This means, however, that products of an inferior quality with a blurred pattern are produced and in some cases the product even has to be rejected, before corrections are finally made. Furthermore, these interventions by the suppliers will cause a waste of time and additional costs.